Spray type heat-exchanging unit

ABSTRACT

A spray type heat-exchanging unit includes a main body; a distributive refrigerant spray module located in an upper part of the main body and having an axially extended distributor and a refrigerant spray surface; and a plurality of heat exchange tubes provided in the main body below the distributive refrigerant spray module. A liquid refrigerant is guided into the axial distributor to drip onto the refrigerant spray surface, and then uniformly sprayed onto the heat exchange tubes. Gaseous refrigerant produced by evaporation in heat exchange in the main body is recovered via a top opening of the main body, making the mechanical refrigerating apparatus more efficient than a refrigerating apparatus adopting a flooded evaporator, and minimizing the refrigerant charge amount and material cost required by the heat-exchanging unit.

FIELD OF THE INVENTION

The present invention relates to a heat-exchanging unit employed in arefrigerant evaporator used by a mechanical refrigerating apparatus, andmore particularly to a spray type heat-exchanging unit.

BACKGROUND OF THE INVENTION

A mechanical refrigerating apparatus includes four major parts, namely,a compressor, an expansion device, a condenser, and an evaporator. Thecurrently available refrigerating systems may be generally divided intothree types, namely, direct expansion type, flooded type, and spraytype, according to the structure of the evaporator thereof. Wherein, theflooded type and the direct expansion type refrigerating system allbelong to a shell-and-tube heat exchanger. In the direct expansion type,refrigerant flows in the tube while the target fluid flows at the shellside. To prevent the liquid refrigerant in the tube from incompleteevaporation and being sucked into the compressor to result in damage ofthe compressor, the direct expansion type refrigerating system must toincrease the superheat at the compressor inlet, which inevitably resultsin high power consumption of the compressor.

In the flooded type refrigerating system, the target fluid flows in thetube while the refrigerant flows at the shell side. Since the liquidrefrigerant is not subject to suction by the compressor at the inletthereof, it is possible to decrease the superheat of the refrigerant atthe compressor inlet and thereby reduce the power consumption of thecompressor. However, since the tube of the flooded type evaporator mustbe immersed in the liquid refrigerant in the shell, an increasedquantity of liquid refrigerant is required to immerse the tube locatedin the shell. As a matter of fact, the quantity of refrigerant requiredin the flooded type refrigerating system is at least twice as much asthat in the direct expansion type refrigerating system to largelyincrease the equipment cost and environmental burden.

In a spray evaporator, the refrigerant is downward sprayed to form aliquid film on the tube in the shell. As being affected by the force ofgravity and other forces, the liquid film of the sprayed refrigerantmoves vertically or in a direction parallel to the tube. When therefrigerant sprayed onto the tube is evaporated, it carries away heatenergy of the target fluid inside the heat exchange tube to achieve thepurpose of heat exchange. Since the liquid refrigerant flows morequickly on the heat exchange tube surface, it is able to evaporate fromthe heat exchange tube surface into gaseous refrigerant within ashortened time. In this manner, the heat exchanger may have an enhancedperformance, and the cost of the heat exchange tube in the shell couldbe reduced by at least 25%. Meanwhile, since it is not necessary toimmerse the heat exchange tube in a large quantity of liquidrefrigerant, the refrigerant charge amount in the mechanicalrefrigerating apparatus may be reduced by more than 20%. However,many-mechanisms in the spray evaporator, such as the refrigerantdistribution control mechanism, have influence on the performance of thespray evaporator. When the mechanism for spraying the refrigerant couldnot be effectively controlled, the sprayed refrigerant shall becomeuniformly distributed on the heat exchange tube to result in unnecessarywaste of energy of the refrigerating apparatus.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a spray typeheat-exchanging unit that enables control of uniform distribution ofliquid refrigerant to effectively increase the refrigerating efficiencyand reduce the material cost of the heat-exchanging unit.

To achieve the above and other objects, the spray type heat-exchangingunit of the present invention includes a main body defining a receivingspace and a top opening; a distributive refrigerant spray module locatedin an upper part of the main body, and having an axially extendeddistributor, a liquid refrigerant inlet, and a refrigerant spraysurface; and a plurality of heat exchange tubes provided in the mainbody below the distributive refrigerant spray module. Liquid refrigerantis guided into the axial distributor via the liquid refrigerant inlet todrip onto the refrigerant spray surface via apertures provided on theaxial distributor, and then uniformly sprayed onto the heat exchangetubes. The liquid refrigerant sprayed onto the heat exchange tubes isevaporated into gaseous refrigerant in the process of heat exchange inthe main body, and the gaseous refrigerant is recovered via the topopening of the main body.

Since the liquid refrigerant is uniformly sprayed onto the heat exchangetubes, the spray type heat-exchanging unit enables improvedrefrigerating efficiency and reduced refrigerant charge amount andmaterial cost.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present inventionto achieve the above and other objects can be best understood byreferring to the following detailed description of the preferredembodiments and the accompanying drawings, wherein

FIG. 1 is a vertical cross-section schematically showing a spray typeheat-exchanging unit according to a preferred embodiment of the presentinvention;

FIG. 2 is a schematic top perspective view of a distributive refrigerantspray module included in the spray type heat-exchanging unit of thepresent invention; and

FIG. 3 shows another embodiment of the refrigerant spray surface of thedistributive refrigerant spray module of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIG. 1 that is a vertical sectional view schematicallyshowing a spray type heat-exchanging unit according to a preferredembodiment of the present invention. As shown, the spray typeheat-exchanging unit of the present invention includes a main body 10, adistributive refrigerant spray module 20, and a plurality of heatexchange tubes 30. The main body 10 has a vertical cross-section similarto a container to define an internal receiving space 11 with a topopening 12. The heat exchange tubes 30 may be staggered or in line in alower part of the receiving space 11 in the main body 10.

Please refer to FIGS. 1 and 2 at the same time. The distributiverefrigerant spray module 20 is located in an upper part of the main body10, and includes an axially extended distributor 21 having a liquidrefrigerant inlet 22 centered at a top thereof and a plurality ofapertures 211 formed on a bottom thereof, and a refrigerant spraysurface 23 provided at a bottom of the module 20 below the axialdistributor 21. As can be seen from FIG. 3, the refrigerant spraysurface 23 includes a plurality of liquid refrigerant spray holes 231.Two splash baffles 24 are extended between the axial distributor 21 andtwo edges of the refrigerant spray surface 23 parallel to the axialdistributor 21, so as to prevent the refrigerant from splashing.

The liquid refrigerant (not shown) is guided into the axial distributor21 via the liquid refrigerant inlet 22 of the distributive refrigerantspray module 20. With the axially extended distributor 21, the liquidrefrigerant is advantageously uniformly distributed along the axialdistributor and drips down to the refrigerant spray surface 23 via theapertures 211 at the bottom of the axial distributor 21. The splashbaffles 24 prevent the dripped liquid refrigerant from splashing. Inanother embodiment of the refrigerant spray surface 23, a porousbuffering material 232, such as chemical fiber non-woven fabrics, plantfiber non-woven fabrics, sponges or sponge-like materials, net fabrics,metal wool, and/or non-metal wool, is provided on a top of therefrigerant spray surface 23, as shown in FIG. 3, so as to absorb theforce produced by the liquid refrigerant that directly impacts againstthe refrigerant spray surface 23, and thereby minimizes the splashing ofthe liquid refrigerant and prevents the liquid refrigerant from beingrapidly sprayed onto the heat exchange tubes 30 via the spray holes 231on the refrigerant spray surface 23 to result in non-uniform spraying ofthe liquid refrigerant. In addition to the round holes illustrated inFIG. 3, the spray holes 231 may also be apertures, slots, or flowpassages with grids, and may be of any other geometrical shapes, so longas the spray holes 231 are able to improve the uniform distribution ofthe liquid refrigerant on a two-dimensional surface.

The downward sprayed liquid refrigerant forms a liquid film on the heatexchange tubes 30. As being affected by the force of gravity and otherforces, the liquid film of the sprayed refrigerant moves vertically orin a direction parallel to the heat exchange tubes 30. When therefrigerant sprayed onto the heat exchange tubes 30 is evaporated, itcarries away heat energy of the target fluid inside the heat exchangetubes 30 to achieve the purpose of heat exchange. Since the liquidrefrigerant flows more quickly on the surfaces of the heat exchangetubes 30, it is able to evaporate from the heat exchange tube surfacesinto gaseous refrigerant within a shortened time. In this manner, theheat-exchanging unit may have an enhanced performance, and the cost ofthe heat-exchanging unit could be reduced by at least 25%. Meanwhile,since it is not necessary to immerse the heat exchange tubes 30 in alarge quantity of liquid refrigerant, the refrigerant charge amount inthe mechanical refrigerating apparatus may be reduced by more than 20%.

The gaseous refrigerant produced by evaporation in the heat exchange mayreturn to the compressor (not shown) via the top opening 12 of the mainbody 10. To further prevent the liquid refrigerant from entering intothe compressor, a liquid separator or other types of baffles orfiltering means (not shown) may be provided at the top opening 12 of themain body 10 to protect the compressor against splashed liquidparticles.

To enhance the refrigerating effect, it is also possible to increase thequantity of the liquid refrigerant, but the refrigerant leftovers willaccumulate in the bottom, so that a part of the heat exchange tubes 30are immersed in the liquid refrigerant. In this manner, it is possibleto effectively increase efficiency of the mechanical refrigeratingapparatus, save valuable energy, and reduce the manufacturing cost ofthe refrigerating apparatus, making the mechanical refrigeratingapparatus more efficient than the refrigerating apparatus adopting theflooded evaporator. As a result, the required refrigerant charge amountand material cost for the heat exchanger are minimized.

The present invention has been described with some preferred embodimentsthereof and it is understood that many changes and modifications in thedescribed embodiments can be carried out without departing from thescope and the spirit of the invention that is intended to be limitedonly by the appended claims.

1. A spray type heat-exchanging unit, comprising: a main body definingan internal receiving space and a top opening communicating with saidreceiving space; a plurality of heat pipes provided in a lower part ofsaid receiving space of said main body; and a distributive refrigerantspray module provided in said main body above said heat exchange tubes,and including an axially extended distributor, a liquid refrigerantinlet, and a refrigerant spray surface; said axial distributor beingprovided with a plurality of apertures, and said liquid refrigerantinlet being provided on a top of said axial distributor for guiding aliquid refrigerant into said axial distributor, so that said liquidrefrigerant drips onto said refrigerant spray surface via said apertureson said axial distributor and be sprayed onto said heat exchange tubes;wherein said liquid refrigerant sprayed onto said heat tubes conductsheat exchange with said heat exchange tubes, and is vaporized intogaseous refrigerant, which flows out of said main body via said topopening of said main body.
 2. The spray type heat-exchanging unit asclaimed in claim 1, wherein said spray surface of said distributiverefrigerant spray module is provided with a plurality of holes.
 3. Thespray type heat-exchanging unit as claimed in claim 1, wherein saidspray surface of said distributive refrigerant spray module is providedwith a plurality of slots.
 4. The spray type heat-exchanging unit asclaimed in claim 1, wherein said spray surface of said distributiverefrigerant spray module is provided with a plurality of flow paths withgrids.
 5. The spray type heat-exchanging unit as claimed in claim 1,wherein said spray surface of said distributive refrigerant spray moduleis provided on a top thereof with a buffering material to minimizesplashing of said liquid refrigerant dripped onto said spray surface. 6.The spray type heat-exchanging unit as claimed in claim 5, wherein saidbuffering material is a porous material.
 7. The spray typeheat-exchanging unit as claimed in claim 6, wherein said porous materialis selected from the group consisting of chemical fiber non-wovenfabrics, plant fiber non-woven fabrics, sponges or sponge-likematerials, net fabrics, metal wool, and non-metal wool.
 8. The spraytype heat-exchanging unit as claimed in claim 1, further comprising twobaffles extended between said axial distributor and said refrigerantspray surface to prevent said liquid refrigerant from splashing.
 9. Thespray type heat-exchanging unit as claimed in claim 1, wherein said heatexchange tubes are staggered in said receiving space of said main body.10. The spray type heat-exchanging unit as claimed in claim 1, whereinsaid heat exchange tubes are orderly arranged in said receiving space ofsaid main body.